Crankcase valve ventilating system



Oct. 1, 1963 w. w. LOWTHER CRANKCASENALVE VENTILATING SYSTEM 2Sheets-Sheet 1 Filed Jan. 8, 1962 11 f /V/V/141 EQIEQRQRK 271271 444 IQ7% [far/er ///wwzysz Oct. 1, 1963 Filed Jan. 8, 1962 W. W. LOWTHER dnfir{far/er United States Patent ()flice BJESA'Z? Patented Get. 1, 19633,105,477 CRANKCASE VALVE VENTILATEJG SYSTEM wimed W. Lowther, Chicago,IlL, assignor to Nova Industrial orporation, New York, N.Y., acorporation of New York Filed Ian. 8, I962, Ser. No. 164,718 11 Claims.(Cl. 123-419) This invention is in the field of crankcase ventilationsystems for internal combustion engines. The invention is concerned witha valve structure for controlling the air flow for ventilating thecrankcase of an internal combustion engine so that the blow-by from thecylinders will not be exhausted to the atmosphere.

A primary object of my invention is a control arrangement for acrankcase ventilating system which is selfcleaning and will not freezeup.

Another object is a valve for controlling the ventilation system of aninternal combustion engine which will not plug up in use.

Another object is a crankcase ventilating system using a floating valveelement.

Another object is a control for a ventilating system which insures anexcess of ventilation over blow-by.

Another object is a crankcase ventilating system which guards againstbackfire.

Another object is a crankcase ventilating system control valve which maybe easily adapted to the particular flow requirements of individualengines.

Another object is using the manifold vacuum to move air in desiredamounts.

Other objects will appear from time to time in'the ensuing specificationand drawings in which:

FIGURE 1 is a schematic of an engine with my ventilation system;

FIGURE 2 is an enlarged sectional view of the valve in FIGURE 1 showingone position of operation;

FIGURE 3 is similar to FIGURE 2 but of another position;

FIGURE 4 is similar to FIGURES 2 and 3 showing the backfire position ofthe valve;

FIGURES 5a through c are of a modified form show- I ing three positionsof operation; and

FIGURES 6, 7 and 8 are graphs showing operating characteristics of theair flow versus manifold vacuum.

In FIGURE 1, I diagrammatically illustrate an engine at 19 which mayhave an air cleaner l2 and a carburetor 14 connected to an intake pipeor manifold 16. The upper portion 18 of the engine may be considered tobe the rocker arm cover. The lower portion 26 may be considered to bethe crankcase. In any event, I may position a breather cap of anysuitable type, as at 22, on the rocker arm cover to admit fresh air tothe inside of the engine. I may connect a passage 24 between the rockerarm cover and the intake pipe and having a valve structure 26 forproviding a controlled flow of ventilating air from the crankcase backto the intake manifold. While I have shown the take-off on top of therocker arm cover, it will be understood that this will provide effectivecommunication between the crankcase and the air intake since the vaporsof the crankcase will flow up through the push rod openings etc. Thearrangement shown in FIGURE 1 is purely diagrammatic.

In FIGURE 2, I have shown the details of the valve structure 26 whichmay include a housing 28 having a generally centrally arranged passage34 leading from an inlet 32 at one end to an outlet 34 at the other. Inthe center of the passage I provide an enlargement 36 which is a chamberfor the valve. The valve is in the form of a pin 38 having a lowerportion as of reduced diameter or dimension and an upper portion 42 of asomewhat enlarged diameter or dimension, interconnected by a taperedportion 44. Above the upper portion, I may reduce the pin somewhat at 46to provide a lower shoulder or abutment 48 with a head 50 above it.

In the lower portion of the housing, I may provide an orifice 52 whichis defined by a sleeve 54 pressed or otherwise held in the lower end ofthe housing. The pin is held in place by a suitable spring, as at 56,which may be a coil spring or otherwise, the bottom of the spring restsagainst the upper shoulder of the orifice, as at 58, while the top restsagainst the shoulder on the pin. It will be noticed that the spring is agenerally tapered coil spring but it may be otherwise. Also, it does nothave to follow a uniform taper. Further, the small coil of the spring isat the top abutting the shoulder of the pin so that therebelow the coilsof the spring move away from the body of the pin so that the pin is heldin a suspended, free condition within the central passage through thehousing. The central passage has a seat 60 above the pin chamber forbackfire purposes.

In FIGURE 2, air from the crankcase enters the inlet 32 and goes outthrough the outlet 34 to the inlet manifold and then back into thecylinders. I have shown the inlet at the top in FIGURE 2, while inFIGURE 1 it would appear that the inlet is at the bottom. But either maybe reversed. The point is that the valve will work with the inlet eitherup or down. So the housing in FIGURE 2 may be turned upside down, andthis may be considered the'FIGURE 1 position. Or I may reverse the valvein the FIGURE 1 arrangement with suitable piping so that the inlet is atthe top with the pin supported on the spring, much like the FIGURE 2position.

FIGURE 2 represents the full load or full speed condition where themanifold vacuum is the least. Whereas FIGURE 3 shows the pin pulled downat the no load or idling or light load condition where the pressuredilIerential across the valve, due to high manifold vacuum, is thegreatest. This may probably be best understood by reference to FIGURE 6.At no load or light loads or idling, the butterfly valve in thecarburetor is closed. Thus, the pistons produce a high vacuum in theinlet manifold. Since the crankcase may he considered to be more or lessat atmospheric pressure due to the opening through the breather 22, thepressure differential across the valve structure will be highest atidling and the low loads and speeds. Due to this high pressuredilferential, the pin will he pulled down into the orifice, such asshown in FIGURE 3, where the upper portion 42 will be generallypositioned in the effective cross section of the orifice, as at 52. Theupper portion 42 of the pin has a diameter or dimension less than theorifice dimension or diameter so that there will be a slight annular orperipheral clearance which will provide for air flow. This is theminimum clearance position and, therefore, the minimum air flowposition. It should be noted that in the FIGURE 3 position, the sides ofthe pin are still out of contact with the orifice even though theclearance is the least. In fact, the pin is suspended on the springwhich is compressed somewhat. Also, the coils of the spring do nottouch, even though they are somewhat closer to each other. In fact, theopen area between the coils is greater, by a great deal, than theminimum clearance area between the upper portion of the pin and theorifice so that the spring does not become a restriction. In otherwords, at no time is the spring compressed solid or anywhere near it.Note in FIGURE 6 that as the engine goes up in load and speed, themanifold vacuum will drop. For example at no load or idling, themanifold vacuum is shown as 20 inches of mercury. Thereafter, as theengine increases in load and speed, the manifold vacuum drops to 18, 16etc. Someplace between 16 and 14 inches of mercury, say, roughly, 15,the pressure differential across the pin has decreased sufliciently suchthat the spring begins to raise the pin. The upper portion 42 of the pincomes up out of the orifice and the tapered portion 44 becomes theeffective part. Since the pin will be falling away from the orifice, soto speak, the effective clearance area between the sides of the taperedportion and orifice will increase. Thus, the opening through the valvewill increase, which will allow a greater air flow. Thus, the curveindicating air flow in FIGURE 6 will move up. The rate of climb may beset by making the taper flatter or steeper. In the example shown in FIG-URE 6, air flow will reach a maximum at something on the order of 8inches of mercury manifold vacuum. Between about 15 and 8 inches ofmercury manifold vacuum, the pin is modulating the air flow by providingan increasing clearance area, shown as approximately a straight linerelationship, as manifold vacuum decreases. Since manifold vacuum is adirect indication of load and speed of the engine, the pin may beconsidered to modulate in direct relation to load and speed. In FIGURE6, from about 8 inches manifold vacuum on up to wide open throttlewhere, theoretically, no pressure differential exists across the pin,the flow through the pin will fall off from the maximum to zero. It willbe noted that the blow-by curve at all times lies below the ventilationflow curve, except possibly at wide open.

Because I can dimension the exterior of the freely floating pin to anydimension I want to gain any particular air flow characteristics, I canmove the break-off which, as shown in FIGURE 6, runs from about 15inches manifold vacuum to about 8 inches, to any suitable location. Inother words, I can move the break-off or slant either left or right onthe graph by dimensioning the pin properly, or changing the springcharacteristics. I can make the Slant steeper or flatter, again by pindimensioning or spring characteristics, or a combination.

To illustrate this point, compare FIGURES 6 and 7. In FIGURE 6, thebreak-off starts at aboutlS inches of mercury manifold vacuum and stopsat about 8, running from an air flow about 1.3 c.f.m. up to about 4.8.If this is undesirable, the break ofi can be shifted, for example to theright in FIGURE 7, by merely forming the different diameters on the pin.For example, in FIGURE 7 the break-off starts at about 11 inches ofmercury manifold vacuum and is completed at about 7 inches, running fromabout 1.3 to about 3.6 c.f.m. air flow. FIGURE 7 has a much steeperbreak-oh? line than FIGURE 6 which starts later and ends slightly later.In effect, the break-ofi line or slant has been moved to the right.Compared to FIGURE 6, however, I could move the break-off line to theleft, again by forming the pin with different diameters.

An important point about my valve structure is that the pin, although itfreely floats in the chamber and does not necessarily havemetal-to-metal contact in any position, nevertheless is dimensionedrelative to the backfire seat and the orifice such that the lower end ofthe pin is always within the orifice. The most extreme position is shownin FIGURE 4 during backfire. The result is that the pin cannot becomerrisaligned, but is held within predetermined limits of movement whileit floats in the housing.

In FIGURE 4, I have shown the pin in a raised position where the head t)rests against the seat 61} which may be considered the backfireposition. It will be noted that the pin will still be centered, more orless, by the spring and will be out of contact with the orifice, but

the lower or small end of the pin will still be within the orifice.Thus, there is no chance, even during backfire, of the pin, in rising toits maximum position, becoming misaligned with the orifice. .Thus, thereis no sticking or jamming.

Further, the spring and pin may be considered to float and the springmay, when backfiring takes place, still (if. rest on the orificeshoulder 53 or it may move up with the pin. In other words, the pin maymove up inside the spring or the spring and pin may move up inside ofthe housing until the head 58 of the pin hits the seat 60.

In FIGURES 5a, b and c, I have shown a modified form in which thehousing may be considered to be the same, the orifice the same, but thepin has been changed somewhat. In this case, the pin 62 has a full taperrunning from the lower end at 64 to an upper edge 66 with an indent 68as a seat for the spring and a head 7t? above it. In this form, theworking portion of the pin, which is the lower part, from 66 to 64,below the head, is the part that cooperates with the orifice and, assuch, I have no cylindrical portions which would correspond to the upperand lower portion in the FIGURE 2 form. Be that as it may, any crosssection along the tapered portion from 64 to '66 may cooperate with theorifice to define an annular clearance area for any particular air flowdesired. FIGURE 5a shows the raised position of the pin in which thelower portion 64 is within and confined by the orifice to define amaximum clearance area which corresponds to the full load or high speedoperation of the engine. The upper portion 66, again on the taper,defines the minimum clearance area with the orifice and corresponds moreor less to the no load or idling or low load and speed operation of theengine. In any event, the full effective length of the pin thatcooperates with the orifice has a dimension throughout which is lessthan the orifice so that in all positions a clearance area, of greateror lesser extent, is defined. Thus, the pin will be suspended and willfloat Within the housing in the same sense that the FIGURE 2 form does.FIGURE 5a corresponds to the idling or low load or low speed positions,While FIGURE 5 b shows the pin in an intermediate position which may beconsidered a modulating position at some intermediate manifold vacuum.

FIGURE 8 is a graph showing the air fiow against manifold vacuum whenusing a pin of the type shown in FIGURE 5 and it will be noted that afar less distinct break-off or rise is present at any given point and,in effect, this valve form will modulate practically throughout itsentire length. It should also be noted that the blow-by curve is at allpoints below the air fiow ventilation except at the extreme right end ofthe range which is the tremendously high speeds where automobiles,trucks, etc. rarely operate. 7

The backfire operation of the pin in FIGURE 5 may be considered to bethe same as that of the FIGURE 2 pm.

In all forms, I may tap the inside of the orifice sleeve, as at 72, sothat if the orifice is to be changed, a bolt may be run in to pull outthe orifice sleeve. But this is option'al.

The use, operation and function of my invention are as follows:

While I have shown the conduit connected to the cover for the rockerarms on top of an engine, it should be understood that it may beconnected at any suitable point where access can be had to the crankcaseof the engine. It will be understood in the form shown in FIGURE 1 thata free flow of the crankcase vapors will be obtained up through the pushrod channels into the cover.

As illustrated by the graphs in FIGURES 6, 7 and 8, my valve has theadvantage that when the pressure differential between the crankcase andthe inlet manifold is highest, at idling and low loads, fiow Will be lowsince the large end or big diameter of the valve element or pin will bein the orifice. Thereafter, as the engine goes up in load and speed andinlet manifold vacuum decreases, the pressure differential across thevalve will also decrease. At the high loads and speeds where thepressure difierential is the least, the spring will move the pin untilthe small diameter is the only portion within the orifice. Thus, theopening will be the greatest and the air flow will be more unrestricted.I shall refer to these as the no load and full load positions, but itshould be understood that these are merely relative terms.

The valve is shown in the full load position in FIG- URE 2 and the smallor lower end of the pin is within and laterally aligned with theorifice. No part of the exterior of the pin is necessarily in contactwith the orifice nor is it in contact with the housing necessarily.Thus, the air flow will separate at the pin into an annular flow on allsides and then reunite when going through the orifice and on to themanifold. The clearance area between the exterior of the small diameterof the pin and the orifice may be accurately and easily controlled bymaking the small portion of the pin either larger or smaller. Thus, thefull load air flow through the control system may be :accurately andeasily controlled. The same is true of the no load position since theclearance area between the large diameter of the pin and the orifice mayalso be easily changed by either enlarging or reducing the diameter ofthe large portion. Also, the characteristics of the valve may be easilychanged by changing the spring. I have shown a conventional tapered coilspring, but it should be understood that in certain situations, I mightuse a spring which in cross section, bowed either in or out, slightlybell shaped, or a combination of springs, one being effective duringonly a certain portion of the pins movement and both effective duringanother portion of the pins movement, as an example, to obtain certainflow and performance characteristics.

In the specification and claims, I have referred to the pin as beinggenerally upright and I have used the terms top, bottom, upper, lower,etc. But it should be understood that these terms are used merely forpurposes of designation and orientation, and the valve will operatesatisfactorily in a horizontal or upside down position; in fact, in anyposition. Thus, in the specification and claims, the terms upper, lower,and the like, should not be interpreted to mean that the valve has to beoperated vertically.

One of the most important points about the operation and structure ofthis valve is that in all positions the pin itself is freely suspendedand is held merely by :a balancing of forces, namely the air pressuredifferential and spring thrust. At no time does the pin bottom against avalve seat, except during backfiring, which is a necessary safetyfeature. But in normal operation, the pin is suspended or floats on thespring with no seating or metalclosing contact with the orifice orsleeve.

In the claims, I have made use of the term upper portion and lowerportion and it should be understood that there may be additionalstructure below the lower portion or above the upper portion. I usethese terms simply to designate the position of the large and smalldiameter portions during the floating operation of the pin. It shouldalso be understood that upper portion and lower portion do not have tobe cylindrical, in the form shown in FIGURE 2. For example, I might havea full taper from one end to the other, such as in FIGURE 5, and the useof the terms upper portion and lower portion may be considered to readon a taper since a given cross section of the taper will be cylindricaland may be considered as the portion in question.

While I show a relatively small angle of divergence on the taper betweenthe two portions in the FIGURE 2 form, it will be understood that thistaper may be more or less. In fact, the taper does not have to follow atrue conical form and the taper in either FIGURE 2 or FIGURE 5 may beslightly concave or convex in axial section if certain flowcharacteristics are desired.

One of the advantages of using a floating pin of this type is that byproperly dimensioning and proportioning the length and the cross sectionrelative to the spring strength and the characteristics of the spring mdalso the orifice opening, I can obtain any combination of air flowcharacteristics at almost any point on the manifold vacuum curve. Thisis shown in the various flow forms of FIGURES 6 through 8. Furthermore,I may move the break-off point either to the left or right, as desired,depending upon the take-0E point of the particular engine and manifioldinvolved. I may make the break-off point as steep as desired, somewhatlike FIG- URE 7, or I may flatten it out, as shown in FIGURE 8. Thecomparison can be shown best by comparing FIG- URES 6 and 7 where thestep-off or break has been shifted somewhat to the right and liesgenerally between 11 and 7 inches of vacuum. In effect, the pin has beenredimensioned or the spring changed or both so that the break-oil orslope has been moved from FIGURE 6 to the right. But it might be theother way.

When the large portion or large diameter of the pin is Within theorifice so that the minimum passage area is available for air flow, atlow loads, the spring thrust is balanced against the vacuum thrust. Inthis condition, however, the spring is not compressed solid and there issufficient opening, in fact, in excess of the cross section of theannular clearance, such that air flow is not effected.

In the various forms shown, I have formed ahead on the pin to abut thesmall end of the spring, and I preferably make the spring flare out fromthe body of the pin there-below, so that the main portion of the pin isfree to move around in the spring. This has the advantage that thedevice will be self-cleaned and will not clog up. Furthermore, it willnot freeze. There are no internal passages or external grooves in thepinto clog or freeze. Further, the spring provides the floating actionwhich normally will center the pin in the passage but at the same timewill allow it to wobble from side to side. Further, the small end of thespring may have a diameter which is just slightly greater than thediameter or dimension of the pin within it so that the pin may shiftlaterally somewhat to accurately self-center itself in the passage.

Since the pin floats and there is no metal-seating contact between thevalve surface and the orifice surface, the pin itself can be made of aninexpensive metal and does not require surface hardening to prevent wearand abrasion. The same is true of the orifice.

In addition to the floating act-ion of the pin, I also get a controlflow by the ability to shape the diameters on the pin to produce anyclearance area I want. Further, the device is simple and is made of aminimum number of parts. For example, I have a housing with a passagethrough it defining a chamber for the pin. One end is large enough toaccept the pin and spring and the orifice can be pressed in and willserve as a support for the large end of the spring. Since I may shapethe etfective diameters along the length of the pin to'any size I wantto get any clearance area I want, I may get a modulated flow of air inthe intermediate part of the taper and not an off-on situation.

In fact, my structure has so few parts that variation in performance canbe quite easily obtained. For example, I may vary the spring, or the pinarea, or the orifice, or a combination. I may taper the pin throughoutits entire length or through only a portion. I may have a single springor a combination of springs to give particular pin movement or a specialpin shape.

Depending upon whether the device is mounted as shown in the drawings orupside down, the loading will be the metering pin plus gravity in onedirection, or the spring less gravity on the other. The connection shownin FIGURE 1 is purely schematic and may be made in any suitable manner.

While I have referred to no metal-to-metal contact or no seatingcontact, it should be understood that the pin will contact the sides ofthe housing and orifice due to engine vibrations. However, this shouldbe distinguished from the metal-to-metal contact that occurs in a normalvalve closing operation. In essence, there is no stop or seat in mystructure to plug up. Further, the airflow itself tends to center thepin, but at the same time the pin is free for lateral oscillation sinceit is only supported loosely at one end.

I have referred to, and the FIGURES 6 through 8 diagrams show, atheoretical manifold vacuum of 0 inch of mercury, and it will beunderstood that in practice this cannot be obtained. I have found, inpractice, that there will be about 1 inch manifold vacuum when thethrottle is wide open.

I have referred to the cross section of the pin as round, and it shouldbe understood that it could be other than round, although I prefer theround cross section.

Also, in FIGURES 2 through 5, I have shown the orifice as an insert, butit should be understood that the orifice or sleeve may be an integralpart of the housing and the inlet or top part 32 may be made as aninsert. In order words, either end may be the insert to allow the pin tobe inserted.

While I have shown and described the preferred form and suggestedseveral modifications of my invention, it should be understood thatsuitable additional modifications changes, substitutions and alterationsmay be made without departing from the inventions fundamental theme. I,therefore, wish that the invention be unrestricted, except as by theappended claims.

I claim:

1. For use in an engine crankcase ventilating system wherein a conduitcommunicates between the engine crankcase and the air intake for thecylinders, 21 valve structure adapted to be positioned in the conduitincluding a valve element and a housing having an orifice therein, thevalve element being positioned in the housing and being in the form ofan elongated solid pin adapted to be disposed normally in a generallyupright position, the pin having a lower portion with a smaller exteriordimension than its upper portion, the body of the pin in between the twoportions being generally tapered, a spring to bias the pin away from theorifice at all times, the at-rest position of the pin, when the springis at its free length, being such that the small cross section lowerportion of the pin will be generally within the confines and laterallyaligned with the orifice, the exterior dimensions of both the upper andlower portions being less than the inside dimension of the orifice, theflow area defined between the lower portion of the pin and the orificebeing substantially greater than the flow area defined between the upperportion of the pin and the orifice, the dimensions of the pin and rateof the spring being such that the pin is out of contact with the orificeunder all load conditions.

2. The structure of claim 1 further characterized in that the loadcharacteristics of the spring are such in relation to the vacuum andpressure conditions of the crarkcase and intake for the cylinders, overthe load and speed range of the engine, such that when there is amaximum pressure differential across the pin to draw the upper portionof the pin into the orifice thereby loading the spring, the pin will beheld in suspension by the balance between the pressure dilferential andthe spring thrust.

3. The structure of claim 1 further characterized by and including ahead portion on the pin above the upper portion having a laterallydisposed shoulder in engagement with the spring.

4. The structure of claim 1 further characterized in that the spring isa compression spring.

5. The structure of claim 1 further characterized by and including ahead portion on the pin above the upper portion having a shoulderdisposed generally laterally thereon and in engagement with the upperend of the spring, the spring being a compression spring, the lower endof the spring resting on the orifice.

amass? 6. For use in an engine crankcase ventilating system wherein aconduit communicates between the engine crankcase and the air intake tothe cylinders, a valve structure adapted to be positioned in the conduitincluding a housing with a generally central passage having a valveenlargement between the ends thereof, with an inlet at one end and anoutlet at the other, a valve element positioned in the enlargement andbeing in the general form of an elongated solid pin adapted to bedisposed generally axially within the housing passage, and an orifice atthe housing outlet, the pin having a lower portion with a smallerexterior dimension than its upper portion, the body of the pin betweenthe two portions being generally tapered, a spring biasing the pin awayfrom the orifice at all times, the at-rest position of the pin, v henthe spring is at its free length, being such that the pin will be out ofcontact with the side Walls of the enlargement and the orifice, thespring engaging the side walls of the enlargement and the pin in amanner such that in all positions of operation the pin floats on thespring out of contact with the side walls of the enlargement.

7. The structure of claim 6 further characterized in that the orifice isin the form of an insert fitted in the outlet of the housing andproviding a shoulder at its inner edge, the spring being generallytapered, small end up, the lower end of the spring resting against theshoulder provided by the orifice insert, the small upper end of thespring engaging the pin.

8. For use in an engine crankcase ventilating system wherein a conduitcommunicates between the engine crankcase and the air intake for thecylinders, a valve structure adapted to be positioned in the conduitincluding a valve element and housing having an orifice therein, thevalve element being positioned in the housing and being in the form ofan elongated pin having a lower portion with a smaller exteriordimension than its upper portion, the body of the pin in between the twoportions being generally tapered, a spring tobias the pin-away from theorifice at all times, the at-rest position of the pin when the spring isat its free length, being such that the flow area defined between thelower portion of the pin and the orifice is substantially greater thanthe flow area defined between the upper portion of the pin and theorifice, the proportioning and dimensioning of the housing, pin, springand orifice being such that the pin is out of contact with the orificeunder all load conditions.

9. .For use in an engine crankcase ventilating system wherein a conduitcommunicates between the crankcase and the air intake for the cylinders,a valve structure adapted to be positioned in the conduit to control theflow of crankcase vapors therethrough, a freely supported flow controlpin in the valve structure, a spring supporting the pin therein so thatthe pin is normally out of contact with the walls of the valve structureother than through its spring support such that the air pressuredifferential through the valve structure operates the pin and spring,the spring being dimensioned such that in its free length, the pin isnormally out of contact with the housing of the valve structure, anorifice in the valve structure downstream from but closely adjacent tothe pin and defining an :efiective flow passage there-with so that asthe air pressure dilferential varies through the passage, causingdifferential movement of the pin, the effective flow passage between thepin and orificejwill be varied in accordance with pin movement, theeifective flow passage being tailored to provide various flow areasbetween the pin and orifice in response to various air pressuredifferentials through the valve structure so that the flow area iscoordinated to the blow-by characteristics of the engine.

10. The structure of claim 9 further characterized in that the pin is ofa length in relation to the free length of the spring such that in theat-rest position of the pin and spring, the downstream end of the pinwill be sure differential cause the coils to effect a sell-cleaninggenerally within the confines and laterally aligned with action With thewalls of the valve structure. the orifice. n

11. The structure of claim 9 further characterized in References Cmd mthe file of this patent that the spring is in the form. of a coilcompression spring 5 UNITED STATES PATENTS disposed about the pin and inengagement with a portion 2,240,459 McDowell Apr. 29, 1941 of the pinupstream from the orifice, the dimensioning 2,423,592 Foster July 8,1947 of the coils of the spring being such that compression 2,906,252Beardsley Sept. 29, 1959 and extension of the spring due to variationsin air pres- 3,017,871 McKiney Jan. 23, 1962

1. FOR USE IN AN ENGINE CRANKCASE VENTILATING SYSTEM WHEREIN A CONDUITCOMMUNICATES BETWEEN THE ENGINE CRANKCASE AND THE AIR INTAKE FOR THECYLINDERS, A VALVE STRUCTURE ADAPTED TO BE POSITIONED IN THE CONDUITINCLUDING A VALVE ELEMENT BEING POSITIONED IN THE HOUSING AND IN, THEVALVE ELEMENT BEING POSITIONED IN THE HOUSING AND BEING IN THE FORM OFAN ELONGATED SOLID PIN ADAPTED TO BE DISPOSED NORMALLY IN A GENERALLYUPRIGHT POSITION, THE PIN HAVING A LOWER PORTION WITH A SMALLER EXTERIORDIMENSION THAN ITS UPPER PORTION, THE BODY OF THE PIN IN BETWEEN THE TWOPORTIONS BEING GENERALLY TAPERED, A SPRING TO BIAS THE PIN AWAY FROM THEORIFICE AT ALL TIMES, THE AT-REST POSITION OF THE PIN, WHEN THE SPRINGIS AT ITS FREE LENGTH, BEING SUCH THAT THE SMALL CROSS SECTION LOWERPORTION OF THE PIN WILL BE GENERALLY WITHIN THE CONFINES AND LATERALLYALIGNED WITH THE ORIFICE, THE EXTERIOR DIMENSIONS OF BOTH THE UPPER ANDLOWER PORTIONS BEING LESS THAN THE INSIDE DIMENSION OF THE ORIFICE, THEFLOW AREA DEFINED BETWEEN THE LOWER PORTION OF THE PIN AND THE ORIFICEBEING SUBSTANTIALLY GREATER THAN THE FLOW AREA DEFINED BETWEEN THE UPPERPORTION OF THE PIN AND THE ORIFICE, THE DIMENSIONS OF THE PIN AND RATEOF THE SPRING BEING SUCH THAT THE PIN IS OUT OF CONTACT WITH THE ORIFICEUNDER ALL LOAD CONDITIONS.